Good question.
I was thinking the same thing.
I don't think we'll know the answer until they start making more games, and get a website up.
I just did a quick search of Yahoo Japan now, and I found about ten different small computer or manufacturing companies called 'Alpha Denshi', but nothing for our ADK. I guess 'Alpha' is a pretty popular name.
Then I did a search under 'DanceRhythMix', and found a few sites with some brief reviews... and all of the sites put question marks after the ADK name, as if they weren't sure if this company was back from the dead or not either!
-H—tŒ´. ƒgƒ‰ƒC ƒAƒ~ƒ…[ƒYƒƒ“ƒgƒ^ƒ[, ƒ_ƒ“ƒXƒŠƒYƒ~ƒbƒNƒXi‚`‚c‚jHHj
-ADKVìiHjMVS‰¹ƒQ[uƒ_ƒ“ƒXƒŠƒYƒ~ƒbƒN ƒXvƒƒPƒeƒXƒg. ƒQ[ƒ€“à—e‚Í‚Æ‚à‚©‚_A‚`‚c‚j‚ª•œŠˆiHj
-ADK•œŠˆ? ƒ_ƒ“ƒXƒŠƒYƒ~ƒbƒNƒX‰¹ƒQ[
I also found this page which has some information about ADK's pre MVS games...
http://www.ngy.1st.ne.jp/~momochi/untiku/alpha.htm